This paper describes the concept of utilizing time synchronized sampling over an entire power system to simultaneously obtain the phasor values of voltages and currents at particular instants of time. Uses of the phasors are reviewed and the necessary accuracy of synchronization for several applications is established for magnitude and angle of the phasors. Various methods of providing synchronizing signals are examined, and a possible format for transmitting the phasor measurements to remote locations is described. Finally, some possibilities for applications of this technique in protection and control tasks of the future are explored. >

Synchronized sampling and phasor measurements for relaying and control

A new method for predicting the rotor angle stability status of a power system immediately after a large disturbance is presented. The proposed two stage method involves estimation of the similarity of post-fault voltage trajectories of the generator buses after the disturbance to some pre-identified templates and then prediction of the stability status using a classifier which takes the similarity values calculated at the different generator buses as inputs. The typical bus voltage variation patterns after a disturbance for both stable and unstable situations are identified from a database of simulations using fuzzy C-means clustering algorithm. The same database is used to train a support vector machine classifier which takes proximity of the actual voltage variations to the identified templates as features. Development of the system and its performance were demonstrated using a case study carried out on the IEEE-39 bus system. Investigations showed that the proposed method can accurately predict the stability status six cycles after the clearance of a fault. Further, the robustness of the proposed method was examined by analyzing its performance in predicting the instability when the network configuration is altered.

Rotor Angle Instability Prediction Using Post-Disturbance Voltage Trajectories

This paper is a summary of the IEEE Power System Relaying Committee report on the System Integrity Protection Schemes (SIPS) survey. The SIPS role is to counteract system instability, maintaining overall system connectivity, and/or to avoid serious equipment damage during major system events. The survey describes industry experiences with this category of protection schemes applied to protect the integrity of the power system. It is designed to provide guidance for SIPS users and implementers based on surveyed operating practices and lessons learned. The survey includes a global participation through the comprehensive effort of IEEE and CIGRE.

IEEE PSRC Report on Global Industry Experiences With System Integrity Protection Schemes (SIPS)

State Estimation and Voltage Security Monitoring Using Synchronized Phasor Measurements

Synchronized Phasor Measurement in Protective Relays for Protection, Control and Analysis of Electric Power Systems

A recently developed predictive out-of-step protection system is described. The purpose of this protection system is to prevent total system collapse caused by step-out between large-capacity generator groups due to a serious fault in the trunk transmission line. This is accomplished by using online data collected during the incubation phase to predict a step-out and then issuing a system-seperation command. The system has the following characteristics: (1) the phase difference between several large generator groups is measured from online voltage data collected from substation busbars in the vicinity of the generators at a sampling rate of 600 Hz: (2) the phase difference at 200 ms in the future is predicted from the measured phase-difference data; and (3) if the predicted phase difference exceeds the instability threshold value, system separation if performed taking into account the power supply and demand balance after tripping. >

K. Yanagihashi

Papers

A predictive out-of-step protection system based on observation of the phase difference between substations